The serum exosomal FECR1 (FLI1 exonic circular RNA) was shown to be markedly higher in patients with SCLC compared with that in heathy individuals and higher levels of exosomal FECR1 could serve as a biomarker of an unfavorable outcome in patients with SCLC [173]. This evidence concerns the gene FLI1 and small cell lung carcinoma.